Aerial spraying of chemicals to control vegetation is known in the art. U.S. Pat. No. 5,137,233 discloses a method of aerial spraying of crops by airplanes with spray jets mounted below and trailing the wings. The method includes directing the spray jets at an acute angle with respect to the lower plane of the wing against a winglet deflection surface of covex shape. The winglet extends at a level distanced from the jet and tilted by an acute tangential angle with respect to the plane of the wing.
U.S. Pat. No. 6,889,776 discloses an apparatus for use with a container of liquid that is suspended from an aircraft flying over a ground target area. The container has an outlet through which the liquid is dropped from the container. The apparatus includes a diffuser configured to diffuse the liquid exiting the container outlet horizontally outward beyond the container into the air about the ground target, whereby the liquid is diffused over a correspondingly wide area.
U.S. Pat. No. 3,428,276 discloses a spraying device detachably connected to an aircraft, in particular a helicopter. The device includes a graduated tank, booms extending outwardly from the tank and wide-angle spray nozzles. A gasoline engine is affixed to a platform seated above the booms. The engine is attached to a pump which pumps the spraying liquid from the tank through the booms and out from the nozzles. The spray pattern is wide dispersal and directed toward the ground.
International Publication No. WO 2004/103063 describes an aerial saw apparatus suspended by a boom from a helicopter. The apparatus includes multiple saw blades, a power source, a pump and a tank. The power source, pump and tank are housed at the lower end of the boom. A series of spray nozzles are interspersed with the saw blades. The pump moves fluid to the spray nozzles where the fluid is sprayed directly on the blade teeth of the aerial saw.